Laser beam machining is the machining processes involving a laser beam kaywretinjourbo.gq Accessed 23 August. Electron Beam Machining (EBM) and Laser Beam Machining (LBM) are Beam Machining (EBM) and high-energy coherent photons in case of Laser. Laser-beam machining is a thermal material-removal process that utilizes a A schematic of laser beam machining is shown in Figure kaywretinjourbo.gq
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𝗣𝗗𝗙 | This paper covers the cutting of commercially-available ceramic tiles using a CO2 laser cutting machine, with the object of producing a. PDF | The paper focuses on laser beam machining (LBM) of In-situ synthesized AlTiB2 metal matrix composite. Optimization and influence of laser. LASER stands for Light Amplification by Stimulated Emission of. Radiation. • LBM uses the light energy (focused coherent beam of monochromatic light) to.
The high intensity of laser beam causes rapid heating of the material, which means that little time is available for heat to dissipate into the surrounding material. Additionally, the reflectivity of most metals is much lower at high intensities, compared to the low beam intensity.
Moreover, the intensity determines the thickness of material which can be cut. Spot size is the irradiated area of laser beam.
In laser cutting application, it is required to focus beam into minimum spot size. Due to the better beam quality of fiber laser with very low divergence, the user can get spot diameters smaller than conventional lasers producing longer working distances.
Continuous wave CW and pulsed laser power Both the continuous wave and pulsed laser power can achieve the high intensity needed for laser cutting. The cutting speed is determined by the average power level. Average power level with CW laser is higher compared to the pulsed laser. All rights reserved by www. Focusing of Laser Beams The focal length of lens is about the distance from the position of focal lens to the focal spot.
Laser beam machining
In the fiber laser system, the laser beam is delivered by the fiber optics and use a collimator to form the divergent laser beam. After that, it comes to the focusing lens or mirror and it focuses the parallel laser beam onto the work piece.
The cutting process requires the spot size is small enough to produce the high intensity power. Focal Position In order to get optimum cutting result, the focal point position must be controlled.
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There are two reasons: the first reason is that the small spot size obtained by focusing the laser beam results in a short depth of focus, so the focal point has to be positioned rather precisely with respect to the surface of the work piece; the other one is differences in material and thickness may require focus point position alterations .
Process Gas and Pressure The process gas has five principle functions during laser cutting.
An inert gas such as nitrogen expels molten material without allowing drops to solidify on the underside dross while an active gas such as oxygen participates in an exothermic reaction with the material.
The gas also acts to suppress the formation of plasma when cutting thick sections with high beam intensities and focusing optics are protected from spatter by the gas flow. The cut edge is cooled by the gas flow thus restricting the width of the HAZ.
The commonly used gases are the oxygen and nitrogen. Nitrogen is mainly used for stainless steel and aluminum, whereas the oxygen is used for mild steel [3, 4]. In the process of oxygen cutting, the presence of oxygen contributes to an exothermic reaction, which effectively increases the laser power.
It results into high cutting speeds and the ability to cut thick material. When cutting thick material, the gas pressure must decrease with the increasing thickness, in order to avoid the burning effect, whereas the nozzle diameter is increased [3, 4]. The nozzle has three main functions in the laser cutting process: to ensure that the gas is coaxial with the beam; to reduce the pressure to minimize lens movements and misalignments; and to stabilize the pressure on the work piece surface to minimize turbulence in the melt pool [3, 4].
The stand-off distance, which is the distance between the nozzle and the work piece, is also an important parameter.
The stand-off distance is usually selected in the same range as the diameter of cutting nozzle-between 0. A short stand-off distance provides stable cutting conditions, although the risk of damage to the lens from spatter is increased. The stand-off distance is optimized to maximum the cutting speed and quality [3, 4]. Cutting Speed The cutting speed must be balanced with the gas flow rate and the power. As cutting speed increases, the cutting time decreases and less time for the heat to diffuse sideways and the narrower the HAZ.
The kerf is also reduced due to the need to deposit a All rights reserved by www. However, striations on the cut edge become more prominent, dross is more likely to remain on the underside and penetration is lost.
When the cutting speed is too low, excessive burning of the cut edge occurs, which degrades edge quality and increases the width of the HAZ. In general, cutting speed for a material is inversely proportional to the thickness. In this paper, multi-objective optimization of the cut quality characteristics such as surface roughness, width of HAZ and kerf width in CO2 laser cutting of stainless steel was presented . J Laser Appl —62 Google Scholar Ivarson A, Powell J, Kamalu J, Magnusson C The oxidation dynamics of laser cutting of mild steel and the generation of striations on the cut edge.
Lasers Eng — Google Scholar Kaplan AFH An analytical model of metal cutting with a laser beam. Fomin VM, A.
Laser Beam Machining
Mahrle A, Beyer E Theoretical aspects of fibre laser cutting. Mathematical modelling of the cut kerf geometry for laser fusion cutting of thick metal. Ivarson A On the physics and chemical thermodynamics of laser cutting.
Powell J, Ivarson A, Magnusson C Laser cutting of steels: a physical and chemical analysis of the particles ejected during cutting.
Principle of Laser Beam Welding This machining process works on basic property of laser. It uses a laser beam, which is a narrow, monochromatic high intense light which can cut or machine any metal and non-metal. It can use to cut any material irrespective to hardness of work piece. It can also use to cut diamond which is hardest known material on earth. This gives power to xenon flash lamps, which produce light energy.
The laser material are exposed in light energy to keep storing energy. Laser Discharge Tube: The laser material filled in lased discharge tube. The excitation of electron and come back to its original state process takes place in it. It is situated between flash lamp. Carbon die oxide is a laser material that emits light in infrared region. It can provide up to 25 KW power in continuous wave mode. The other one is called Neodymium doped Yttrium Aluminum Garnet is a solid state laser which can delivery light through optical fiber.
It can generate about 50 KW power in pulsed mode and 1 KW power in continuous mode. Focusing Lens: A focusing lens is used in laser machining operation. It is a convex lens which focus is at work piece.Application: Used to drill small hole of diameter about 0. Its process can be summarized as follow.
The results show that the laser variables significantly influence the process response. The applied methodology integrates modelling of the relationships between the laser cutting factors laser power, cutting speed, assist gas pressure and focus position and cut quality characteristics using ANNs, formulation of the multi-objective optimization problem using weighting sum method and solving it by CSA Comparative Sequence Analysis.
While machining some plastics bum or char is noticed.
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